Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for reporting channel state information in a wireless communication system.
Related Art
3rd generation partnership project (3GPP) long term evolution (LTE) evolved from a universal mobile telecommunications system (UMTS) is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) evolved from the 3GPP LTE.
As disclosed in 3GPP TS 36.211 V10.4.0 (2011-12) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 10)”, a physical channel of the LTE can be classified into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
The uplink channel is used to transmit a variety of uplink control information such as hybrid automatic repeat request (HARQ) positive-acknowledgement (ACK)/negative-acknowledgement (NACK), channel state information (CSI), and scheduling request (SR).
With the introduction of a scheme of increasing channel capacity such as multiple input multiple output (MIMO) and carrier aggregation (CA), an amount of uplink control information is also increased. A radio resource for an uplink channel may be more restrictive than a radio resource for a downlink channel, and a transmission error of the uplink control information may aggravate service quality.
There is a need to design a coding and power control for an uplink channel according to an increasing amount of the uplink control information.